PULLMAN, Wash.  Behold the cheerleader: definition of popularity, goddess of the school and object of desire.

But it wasn't always so. Cheerleading began in the late 1800s as a way for men to display leadership potential. It evolved after World War II into a beauty-obsessed ideal of femininity.

More recently, it has changed again, into an athletic discipline for both sexes based on gymnastics.

"You can learn a lot about American society through cheerleading," said Washington State University professor Pamela Bettis, co-author of the new book, "Cheerleader!: An American Icon."

It's all here, from the early days in the Ivy League, to the big megaphones, the pompons, the Dallas Cowboys cheerleaders and the homicidal Texas cheerleader mom. There are 3.8 million cheerleaders in the United States, the authors found.

Bettis, an unsuccessful cheerleader candidate, co-wrote the book with former cheerleader Natalie Guice Adams of the University of Alabama. They describe it as an activity as American as jazz and baseball.

The book began as an academic study of leadership among adolescent girls, Bettis said. The authors found that their interview subjects were constantly mentioning cheerleaders as leaders, so they decided to change their focus.

"This is not a book I ever expected to write," Bettis said.

Cheerleading is ingrained in our culture.

MTV is running "Camp Jim," a reality series about training to be a cheerleader.

Many girls either aspire to be cheerleaders or feel oppressed by them. Dating a cheerleader conveys status on males. These attitudes show up constantly in popular culture, where cheerleaders are often lampooned or maligned, Bettis said.

Consider the self-absorbed Spartan cheerleaders on "Saturday Night Live"; the hyper-competitive cheerleaders in "Bring It On" "I'm sexy, I'm cute, I'm popular to boot"); and the bank-robbing cheerleaders in the movie "Sugar and Spice."

Cheerleading started as an all-male activity at elite colleges in the East. Hoisting a big megaphone to exhort one's classmates to victory was a sign of high status.

"If you could lead rowdy students during rowdy football games, you could be a leader in the emerging industrial order," Bettis said. "It was as high status as being quarterback of the football team."

Which may explain why Dwight Eisenhower and other presidents were cheerleaders.

During World War II, women largely replaced the men who were off to war. As a result, cheerleading lost status as a male activity and became associated almost exclusively with females. In the 1970s, cheerleading became highly sexualized, illustrated by the popularity of the Dallas Cowboys cheerleaders.

Then the sport changed again, becoming an athletic competition that required gymnastics ability for its high-flying routines.

These days cheerleading combines traditional notions of feminine beauty with athletic ability, explaining its continued popularity, Bettis said. Cheerleading also avoids the lesbian overtones some people place on rough-and-tumble women's sports such as softball and basketball, Bettis said.

"You don't question the sexual orientation of a cheerleader," she said.

That's not the case for men, who are returning to cheerleading, especially in college, as the activity becomes more athletic. They are still being labeled effeminate, Bettis said.

"Every male cheerleader said they face that critique," Bettis said.

Cheerleading recently has become an instrument of social change, as many protest groups use cheer tactics in public demonstrations.

Sheila Noone, editor of American Cheerleader in New York City, said the magazine concentrates on the athletic nature of cheerleading. These days there are cheerleaders who specialize in sporting events, and others who focus exclusively on competitions.

Competition cheering has seen the most dramatic increase in popularity. There are some 800 gyms in the United States providing training for such competitions, Noone said.

The magazine picks a cheerleader of the month, an award that depends on grades and community service, Noone said. "We want them to use their power for good," she said.

Cheerleading also gets steady attention in the news pages. Perhaps the best-known case was in 1991, when Wanda Holloway was charged with trying to hire a hit man to kill the mother of her 13-year-old daughter's cheerleading rival in Houston. Holloway, who served six months in prison, hoped the grieving daughter would drop out of tryouts for the school cheerleading squad.

In September, officials of Elma High School in Elma, Wash., banned the school cheerleaders from wearing their short skirts in halls and classrooms, saying that violated the dress code. Now the outfits will be allowed only at games and other performances.

Bettis said this illustrates one of the darker elements of cheerleading, "a place for girls to try out sexuality in public form."